Method of making an integrated optical detector

Abstract

There is disclosed an integrated optical detector comprising a semiconductor substrate having an optical waveguide formed integrally therewith and a photodetector made from the same semiconductor material as the waveguide and integrally coupled to it. The detector region is sensitive to light of the same wavelengths that can be transmitted through the waveguide region of the semiconductor without excessive absorption therein by virtue of the fact that after the waveguide is formed proton bombardment of the detector portion thereof is used to create optically active defect centers thereby shifting the effective absorption edge in the detector region. Where gallium arsenide is used as the semiconductor defect levels induced by implantation of high energy protons give rise to optical absorption between 6 micron and 0.9 micron. This results in detector action in the presence of a Schottkey barrier depletion layer. Detector response times less than 200 nanoseconds and external quantum efficiencies of 16 percent have been observed in the device.

What is claimed is: 
     
       1. In a process of fabricating an integrated optical device which includes the step of forming a light transmissive waveguide in a semiconductor substrate, the improvement comprising: a. proton irradiating a selected portion of said waveguide to form an active photodetector region integral with said waveguide by creating optically active defeat centers in said region to thereby shift the effective wavelength absorption edge therein to render said photodetector region sensitive to light of wavelengths that can be transmitted through said waveguide; and   b. forming a Schottkey barrier diode type electrode on the proton irradiated region and an ohmic contact electrode on said substrate.   
     
     
       2. A process as in claim 1 wherein said Schottkey barrier electrode is formed by evaporation deposition of metal. 
     
     
       3. A process as in claim 2 wherein said metal is aluminum and said waveguide is formed of gallium arsenide. 
     
     
       4. A process as in claim 1 wherein said Schottkey barrier electrode is formed by evaporation deposition of a transparently thin metallic layer. 
     
     
       5. A process as in claim 4 wherein said metal is gold and said waveguide is formed of gallium arsenide.